Wiring substrate and method of manufacturing the same

ABSTRACT

A wiring substrate includes a composite substrate including an oxidized aluminum substrate portion in which a large number of penetration conductors penetrating in a thickness direction are provided, and a frame-like aluminum substrate portion provided around the oxidized aluminum substrate portion, and a wiring layer of n layers (n is an integer of 1 or more) connected to the penetration conductors.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2010-054149, filed on Mar. 11,2010; the entire contents of which are incorporated herein by reference.

FIELD

It is related to a wiring substrate including a large number ofpenetration conductors that enable the conduction between upper andlower surface sides of the substrate, and a method of manufacturing thesame.

BACKGROUND

In the prior art, there exists the multilayer wiring substrate formounting a semiconductor chip. In the multilayer wiring substrate, thebuild-up wiring is formed on both surface sides of the core substrate,and also the chip connection pads for mounting the semiconductor chipare provided on one surface and the external connection pads areprovided on the other surface.

In Patent Literature 1 (Japanese Laid-open Patent Publication No.2004-273480), it is set forth that the wiring substrate is constructedbased on such a manner that the conductive material is buried in thethrough holes, which are located in the area where the electrodes arearranged, out of a large number of through holes in the porous oxidizedaluminum formed by the anodic oxidizing method, whereas the insulatingmaterial is buried in the through holes located in the area except it.

In Patent Literature 2 (Japanese Laid-open Patent Publication No.2009-147241), it is set forth that the circuit substrate is constructedby forming the insulating layer, in which the opening portions to exposethe selected through-hole conductors are provided, on both surfaces ofthe porous alumina substrate having a plurality of through-holeconductors, and then forming the wirings which are connected to thethrough-hole conductors in the opening portions.

As described later, in the related art, the wiring substrate ismanufactured based on such a manner that the build-up wiring is formedon the thin oxidized aluminum substrate in which a large number ofpenetration conductors are provided. The oxidized aluminum substrateincluding a large number of penetration conductors is in a fragilecondition because rigidity of the substrate is weak.

As a result, when the build-up wiring layer is formed on the oxidizedaluminum substrate, cracks easily occur in the oxidized aluminumsubstrate.

Also, the fine penetration conductors are provided up to the edge partof the oxidized aluminum substrate. As a result, when a mechanicalimpact is given during the manufacturing step, or the like, in somecases the penetration conductors fall to peel off from the edge part ofthe oxidized aluminum substrate.

SUMMARY

According to one aspect discussed herein, there is provided a wiringsubstrate, which includes an oxidized aluminum substrate portion inwhich a large number of penetration conductors penetrating in athickness direction are provided, and a frame-like aluminum substrateportion provided around the oxidized aluminum substrate portion, and awiring layer of n layers (n is an integer of 1 or more) connected to thepenetration conductors.

According to another aspect discussed herein, there is provided a methodof manufacturing a wiring substrate, which includes preparing acomposite substrate, which includes a plurality of oxidized aluminumsubstrate portions in each of which a large number of penetrationconductors which penetrate in a thickness direction are provided, and analuminum substrate portion which couples the plurality of oxidizedaluminum substrate portions, and forming a wiring layer of n layers (nis an integer of 1 or more) connected to the penetration conductors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1D are sectional views (#1) depicting a method ofmanufacturing a wiring substrate in the related art;

FIGS. 2A to 2C are sectional views (#2) depicting the method ofmanufacturing the wiring substrate in the related art;

FIGS. 3A to 3C are sectional views (#3) depicting the method ofmanufacturing the wiring substrate in the related art;

FIGS. 4A to 4D are sectional views (#1) depicting a method ofmanufacturing a wiring substrate according to a first embodiment;

FIGS. 5A to 5D are sectional views (#2) depicting the method ofmanufacturing the wiring substrate according to the first embodiment;

FIGS. 6A to 6C are sectional views (#3) depicting the method ofmanufacturing the wiring substrate according to the first embodiment;

FIGS. 7A and 7B are sectional views (#4) depicting the method ofmanufacturing the wiring substrate according to the first embodiment;

FIG. 8 is a sectional view depicting a wiring substrate according to thefirst embodiment;

FIG. 9 is a sectional view depicting a semiconductor package accordingto the first embodiment;

FIGS. 10A to 10C are sectional views depicting a method of manufacturinga wiring substrate and a semiconductor package according to a secondembodiment;

FIGS. 11A to 11C are sectional views depicting a method of manufacturinga wiring substrate and a semiconductor package according to a thirdembodiment; and

FIGS. 12A to 12C are sectional views depicting a method of manufacturinga wiring substrate and a semiconductor package according to a fourthembodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be explained with reference tothe accompanying drawings hereinafter.

(Related Art)

Prior to the explanation of respective embodiments, the related art(preliminary matter) will be explained hereunder. FIG. 1A to FIG. 3C aresectional views depicting a method of manufacturing a wiring substratein the related art.

In the method of manufacturing the wiring substrate in the related art,as depicted in FIG. 1A, first, an aluminum (Al) substrate 100 a isprepared.

The aluminum substrate 100 a is the multi production substrate, and aplurality of wiring substrate regions A are defined thereon.

Then, as depicted in FIG. 1B, an oxidized aluminum substrate 100 isobtained by anodizing the aluminum substrate 100 a from the surfaceside. At this time, a large number of fine holes H are formedsimultaneously from the whole surface of the oxidized aluminum substrate100 toward the thickness direction. Also, such a situation is obtainedthat an aluminum portion 100 b that is not anodized is left to the lowerside of the oxidized aluminum substrate 100.

Then, as depicted in FIG. 1C, the aluminum portion 100 b which is leftto the lower side of the oxidized aluminum substrate 100 is removed bythe etching. Accordingly, the oxidized aluminum substrate 100 in which alarge number of through holes TH each of which penetrates the substratefrom the upper surface to the lower surface are provided side by side inthe lateral direction is obtained. The oxidized aluminum substrate 100is formed as the thin type substrate whose thickness is about 100 μm.

Then, as depicted in FIG. 1D, a plating power feeding layer (not shown)is arranged on the lower surface of the oxidized aluminum substrate 100in which a large number of through holes TH are provided. Then, thecopper plating is applied to the inside of the through holes TH from thebottom part to the upper part by the electroplating. Thus, a penetrationconductor TC is filled in the through holes TH respectively.

Accordingly, the oxidized aluminum substrate 100 in which thepenetration conductor TC (linear conductor) is filled in a large numberof through holes TH respectively is obtained.

Then, as depicted in FIG. 2A, a first interlayer insulating layer 200made of an insulating resin is formed on both surface sides of theoxidized aluminum substrate 100 respectively. Also, the first interlayerinsulating layer 200 formed on both surface sides respectively isprocessed by the CO₂ laser, and thus first via holes VH1 each reachingthe both end part of the penetration conductor TC are formedrespectively. A plurality of penetration conductors TC arranged in thefirst via holes VH1 function as the penetration vias which penetrate tothe both surface sides of the oxidized aluminum substrate 100.

Then, as depicted in FIG. 2B, first wiring layers 300 each connected tothe penetration conductor TC via the first via hole VH1 are formed onthe first interlayer insulating layer 200 on both surface sidesrespectively. The first wiring layers 300 formed on both surface sidesare connected mutually via the penetration conductor TC.

Then, as depicted in FIG. 2C, a second interlayer insulating layer 220,in which second via holes VH2 each reaching the connection part of thefirst wiring layer 300 are provided, is formed on both surface sides ofthe oxidized aluminum substrate 100 by the similar method respectively.Then, second wiring layers 320 each connected to the first wiring layer300 via the second via hole VH2 are formed on the second interlayerinsulating layer 220 on both surface sides respectively.

Then, as depicted in FIG. 3A, a solder resist 240, in which an openingportion 240 a is provided on the connection parts of the second wiringlayers 320 respectively, is formed on both surface sides of the oxidizedaluminum substrate 100 respectively.

Then, as depicted in FIG. 3B, a nickel/gold plating layer is formed onthe connection parts of the second wiring layers 320 on both surfacesides of the oxidized aluminum substrate 100 respectively, and thuscontact layers 340 are obtained respectively. Then, a solder bump 360connected to the second wiring layer 320 is formed in the openingportions 240 a in the solder resist 240 on both surface sides of theoxidized aluminum substrate 100 respectively.

Accordingly, a wiring member 400 constructed such that a build-up wiringlayer is formed in a plurality of wiring substrate regions A of theoxidized aluminum substrate 100 respectively is obtained.

Then, as depicted in FIG. 3C, individual wiring substrates 420 areobtained by cutting the wiring member 400 in FIG. 3B between the wiringsubstrate regions A. The connection parts of a semiconductor chip 500are flip-chip connected to the solder bumps 360 of the wiring substrate420. Accordingly, a semiconductor package 440 constructed such that thesemiconductor chip 500 is mounted on the wiring substrate 420 isobtained.

As described above, in the method of manufacturing the wiring substratein the related art, the wiring substrate 420 is manufactured based onsuch a manner that the build-up wiring layer is formed on the thinoxidized aluminum substrate 100 in which a large number of penetrationconductors TC are provided. Since the oxidized aluminum substrate 100 ismade thin to have a thickness of about 100 μm and also has such astructure that the penetration conductors TC are provided over the wholesurface, rigidity of the substrate is weak and also the substrate is ina fragile condition.

Therefore, when the build-up wiring layer is formed on both surfacesides of the oxidized aluminum substrate 100, cracks easily occur in theoxidized aluminum substrate 100. Also, the enough substrate strengthcannot be obtained even after the semiconductor package 440 isconstructed by mounting the semiconductor chip 500 on the wiringsubstrate 420.

Further, the fine penetration conductors TC are provided up to the outeredge parts of the oxidized aluminum substrate 100. Therefore, when amechanical impact is given during the manufacturing step and after thesemiconductor package is constructed, in some cases the penetrationconductors TC fall to peel off from the outer edge part of the oxidizedaluminum substrate 100.

In this manner, in the method of manufacturing the wiring substrate inthe related art, it is difficult to obtain a satisfactory manufacturingyield, and also it is feared that reliability of the wiring substrateand the semiconductor package becomes an issue.

Respective wiring substrates of embodiments explained hereinafter cansolve such disadvantages.

First Embodiment

FIG. 4A to FIG. 7B are sectional views depicting a method ofmanufacturing a wiring substrate according to a first embodiment, FIG. 8is a sectional view depicting a wiring substrate according to the firstembodiment, and FIG. 9 is a sectional view depicting a semiconductorpackage according to the first embodiment.

In the method of manufacturing the wiring substrate according to thefirst embodiment, as depicted in FIG. 4A, first, an aluminum (Al)substrate 10 a is prepared. The aluminum substrate 10 a is the multiproduction substrate, and a plurality of wiring substrate regions A aredefined thereon. In FIG. 4A, two wiring substrate regions A areillustrated, but any number of wiring substrate regions A may bedefined.

Then, as depicted in FIG. 4B, an insulating resin layer 11 in which anopening portion 11 a is provided in center principal portions of thewiring substrate regions A respectively is formed on the aluminumsubstrate 10 a. The opening portions 11 a of the insulating resin layer11 are arranged in regions that are to be anodized in the aluminumsubstrate 10 a.

The insulating resin layer 11 in which the opening portions 11 a areprovided is obtained by forming a photosensitive epoxy resin, or thelike on the aluminum substrate 10 a, and then exposing/developing theresin by means of the photolithography. Preferably a photoresist isemployed as the insulating resin layer 11.

Otherwise, as the insulating resin layer 11, an adhesive tape in whichopening portions are provided in advance may be pasted onto the aluminumsubstrate 10 a.

As depicted in a reduced plan view in FIG. 4B, the opening portions 11 aof the insulating resin layer 11 are arranged such that the pattern ofthe insulating resin layer 11 is formed in grid-like fashion. Andrespective regions located between the opening portions 11 a are used asdicing regions D, and the dicing regions D are covered with theinsulating resin layer 11. The dicing regions D are used as the cuttingregions for obtaining individual wiring substrates by cutting the multiproduction substrate.

Then, as depicted in FIG. 4C, the electrolysis using the aluminumsubstrate 10 a as the anode is applied in a treatment bath such as anoxalic acid solution, or the like. Accordingly, the aluminum substrate10 a in the opening portions 11 a of the insulating resin layer 11 isanodized in the thickness direction, and thus an oxidized aluminumsubstrate portion 10 is obtained.

Depending on the conditions of the anodic oxidation, in some cases theoxidized aluminum may grow in the lower side of the insulating resinlayer 11. Such growth can be suppressed by optimizing the conditions ofthe anodic oxidation.

At this time, the aluminum substrate 10 a is made porous by the anodicoxidation. Therefore, a large number of fine holes H are formedsimultaneously from the surface of the oxidized aluminum substrateportion 10 in the opening portions 11 a of the insulating resin layer 11toward the thickness direction.

Also, such a situation is obtained that a thin aluminum portion 10 bthat is not anodized is left in the lower side of the oxidized aluminumsubstrate portion 10.

Since respective regions (dicing regions D) of the aluminum substrate 10a, where are covered with the insulating resin layer 11, are notanodized, such portions are left as an aluminum substrate portion 10 xfrom the upper surface to the lower surface.

Then, as depicted in FIG. 4D, the aluminum portion 10 b left in thelower side of the oxidized aluminum substrate portion 10 is removed bythe etching until the holes H are exposed.

Accordingly, the oxidized aluminum substrate portion 10 in which a largenumber of through holes TH which penetrate from the upper surface to thelower surface are provided side by side in the lateral direction isobtained, and simultaneously the aluminum substrate portion 10 x iscoupled between a plurality of oxidized aluminum substrate portions 10.

As depicted in a fragmental plan view in FIG. 4D, a large number ofthrough holes TH are arranged side by side in the substrate direction insuch a state that these holes are separated mutually via the oxidizedaluminum substrate portion 10.

As the preferred embodiment, a thickness of the oxidized aluminumsubstrate portion 10 is set to about 70 to 120 μm, a diameter of thethrough hole TH is set to 60 to 200 nm, and a pitch of the through holesTH is set to 100 to 300 nm.

In this manner, the oxidized aluminum substrate portion 10 in which alarge number of through holes TH are provided is arranged in the areascorresponding to the opening portions 11 a of the insulating resin layer11 respectively, and the non-oxidized aluminum substrate portion 10 x isarranged in the areas corresponding to the dicing regions Drespectively.

With the above, a composite substrate 5 having such a structure that aplurality of oxidized aluminum substrate portions 10 are coupledmutually via the aluminum substrate portion 10 x is obtained.

As explained in the related art, substrate strength of the oxidizedaluminum substrate portion in which a large number of through holes THare provided over the whole area is weak, thus the cracks easily occurin the later manufacturing steps. In the present embodiment, a pluralityof oxidized aluminum substrate portions 10 are coupled mutually by thealuminum substrate portion 10 x whose substrate strength is relativelystrong. Therefore, the strength in the whole substrate is reinforced,and such an event is prevented that the cracks are caused in the latermanufacturing steps.

Here, in the anodic oxidizing step in FIG. 4C, the aluminum substrate 10a may be anodized in such a state that a protection metal layer (notshown) is formed on the lower surface of the aluminum substrate 10 a. Inthis case, the anodic oxidation can be applied to the part closer to thelower surface of the aluminum substrate 10 a. Then, the protection metallayer and the aluminum portion 10 b are removed by the etching.

Also, in place of the aluminum substrate 10 a, a tantalum (Ta) substrateor a titanium (Ti) substrate may be employed. In this case, thecomposite substrate, in which a plurality of oxidized tantalum substrateportions (or oxidized titanium substrate portions) are coupled mutuallyby a tantalum substrate portion (or a titanium substrate portion), isobtained by carrying out the similar steps.

Then, as depicted in FIG. 5A, a plating power feeding layer 12 is formedon the opposite surface side to the surface of the composite substrate 5on which the insulating resin layer 11 is formed. As the plating powerfeeding layer 12, either a copper foil, or the like may be temporarilyadhered or a titanium (Ti) layer/a copper (Cu) layer may be formed insequence from the bottom by the sputter method.

Then, the copper (Cu) plating is applied to respective insides of thethrough holes TH in the oxidized aluminum substrate portion 10 from thebottom part to the top part by the electroplating utilizing the platingpower feeding layer 12 as a plating power feeding path. Thus, apenetration conductor TC (linear conductor) is filled in the throughholes TH respectively. Here, the penetration conductors TC may be formedof nickel by applying the nickel (Ni) plating in place of the copperplating.

Otherwise, the penetration conductor TC can be filled selectively in thethrough holes TH in the oxidized aluminum substrate portion 10 byapplying the electroless plating in place of the electroplating.

Then, as depicted in FIG. 5B, the plating power feeding layer 12 isremoved from the composite substrate 5. Then, the insulating resin layer11 formed on the composite substrate 5 is removed. In the case that thephotoresist is employed as the insulating resin layer 11, the insulatingresin layer 11 is removed by applying the ashing or an organic solvent(resist stripper). Alternatively, in the case that an adhesive tape isemployed as the insulating resin layer 11, such adhesive tape is peeledoff.

Accordingly, the composite substrate 5 which includes a plurality ofoxidized aluminum substrate portions 10 in which a large number ofpenetration conductors TC are provided, and the aluminum substrateportions 10 x which couple the oxidized aluminum substrate portions 10is obtained. As depicted in a fragmental plan view of FIG. 5B, a largenumber of penetration conductors TC are arranged side by side in thesubstrate direction in such a state that these conductors TC areinsulated mutually with the oxidized aluminum substrate portion 10(insulator).

The aluminum substrate portion 10 x of the composite substrate 5reinforces the oxidized aluminum substrate portion 10 whose substratestrength is weak in the later manufacturing steps, and also the aluminumsubstrate portion 10 x is left as a frame-like stiffener (reinforcingplate) to the outer edge side of the wiring substrate after the aluminumsubstrate 10 a is cut along the dicing region D (FIG. 4B).

Next, a method of forming a build-up wiring layer on both surface sidesof the composite substrate 5 having such structure will be explainedhereunder.

Then, as depicted in FIG. 5C, first, a first interlayer insulating layer20 formed of an insulating resin such as epoxy resin, polyimide resin,or the like is formed on both surface sides of the composite substrate 5respectively. A film thickness of the first interlayer insulating layer20 is set to 20 to 40 μm.

Then, as depicted in FIG. 5D, the first interlayer insulating layer 20is processed on both surface sides of the composite substrate 5 by theCO₂ laser. Thus, first via holes VH1 each reaching an upper end or alower end of the penetration conductor TC provided in the oxidizedaluminum substrate portion 10 are formed respectively. A plurality ofpenetration conductors TC which are arranged in the first via holes VH1in the first interlayer insulating layer 20 function as the penetrationvias that enable the conduction between upper and lower surface sides ofthe composite substrate 5.

Otherwise, a photosensitive insulating resin may be formed on bothsurface sides of the composite substrate 5, and then the first via holesVH1 may be formed by exposing/developing the photosensitive insulatingresin by means of the photolithography.

In the present embodiment, the first via holes VH1 in the firstinterlayer insulating layer are arranged in any positions of theoxidized aluminum substrate portion 10 in which a large number ofpenetration conductors TC are provided in advance. Therefore, thepenetration via structure that enable the conduction between bothsurface sides can be easily constructed. As a result, the high-densityconnection via structure can be formed at a low cost without restrictionof layout of the penetration vias.

Then, as depicted in FIG. 6A, first wiring layers 30 each connected toupper ends or lower ends of the penetration conductors TC via the firstvia holes VH1 are formed on both surface sides of the first interlayerinsulating layer 20 respectively. The first wiring layers 30 are formedby the semi-additive process, for example.

To explain in detail, a seed layer (not shown) is formed on the firstinterlayer insulating layer 20 and in the first via holes VH1 on bothsurface sides of the composite substrate 5. As the seed layer, alaminated film in which a titanium (Ti) layer whose film thickness is 50nm and a copper layer whose film thickness is 500 nm are laminated inorder from the bottom is used.

Then, a plating resist (not shown), in which opening portions areprovided in parts where the first wiring layer 30 is arranged, is formedon the seed layer. In subsequent, a metal plating layer (not shown) isformed in the opening portions by the electroplating utilizing the seedlayer as a plating power feeding path. As the metal plating layer, acopper layer whose film thickness is about 20 μm is used.

Then, the plating resist is removed, and then the seed layer is etchedwhile using the metal plating layer as a mask. Thus, the first wiringlayer 30 constructed by the seed layer and the metal plating layer isobtained.

In the connection part of the first wiring layer 30 and the penetrationconductors TC, the first wiring layer 30 is connected electrically to aplurality of penetration conductors TC.

Also, the first wiring layer 30 is formed to include first wiringportions 30 a and first substrate reinforcing electrode portions 30 b.The first wiring portion 30 a is arranged on both surface sidescorresponding to the oxidized aluminum substrate portion 10 and isconnected to the penetration conductors TC. The first substratereinforcing electrode portion 30 b is arranged via the first interlayerinsulating layer 20 on both surface sides corresponding to the aluminumsubstrate portion 10 x.

The first substrate reinforcing electrode portions 30 b are formed to beseparated from the first wiring portions 30 a, and are formed as thefloating electrode that is not connected to the electric circuit whichis constructed by the penetration conductor TC, the first wiring portion30 a, and the like.

As depicted in a fragmental reduced plan view of FIG. 6A, the firstsubstrate reinforcing electrode portions 30 b (hatched portions) arearranged in the parts corresponding to the aluminum substrate portions10 x in a state that these portions are connected to surround aplurality of oxidized aluminum substrate portions 10. That is, whenviewed from the top, the first substrate reinforcing electrode portions30 b are formed with a grid-like pattern that is smaller by one sizethan the aluminum substrate portions 10 x which are arranged with agrid-like pattern.

The first substrate reinforcing electrode portions 30 b are arranged ingrid-like fashion on both surface sides of the aluminum substrateportion 10 x, thus substrate strength of the composite substrate 5 canbe improved further more.

The first substrate reinforcing electrode portions 30 b may be arrangedseparately mutually, but substrate strength can be reinforced much moreby arranging the substrate reinforcing electrode portions with aring-like connected pattern.

Then, as depicted in FIG. 6B, a second interlayer insulating layer 22 inwhich second via holes VH2 are provided on the first wiring layer 30 isformed on both surface sides of the composite substrate 5 respectivelyby the similar method.

Then, as depicted in FIG. 6C, second wiring layers 32 each connected tothe first wiring layer 30 via the second via holes VH2 are formed onboth surface sides of the second interlayer insulating layer 22 by thesimilar method.

Like the first wiring layer 30, the second wiring layer 32 is formed toinclude second wiring portions 32 a and second substrate reinforcingelectrode portions 32 b. The second wiring portion 32 a is arranged onboth surface sides corresponding to the oxidized aluminum substrateportion 10, and is connected to the first wiring portions 30 a of thefirst wiring layer 30 via the second via holes VH2. Also, the secondsubstrate reinforcing electrode portion 32 b is arranged on both surfacesides corresponding to the aluminum substrate portions 10 x via thesecond interlayer insulating layer 22.

Like the first wiring layer 30, it is preferable that the secondsubstrate reinforcing electrode portions 32 b of the second wiring layer32 should be arranged with a ring-like connected pattern on the partscorresponding to the aluminum substrate portions 10 x. Also similarly,the second substrate reinforcing electrode portions 32 b of the secondwiring layer 32 are not connected to the electric circuit and are formedas the floating electrode.

The first substrate reinforcing electrode portions 30 b of the firstwiring layer 30 and the second substrate reinforcing electrode portions32 b of the second wiring layer 32 are stacked on both surface sides ofthe aluminum substrate portions 10 x, thus substrate strength of thecomposite substrate 5 can be improved further more.

Since the first and second substrate reinforcing electrode portions 30b, 32 b of the first and second wiring layers 30, 32 are not connectedto the electric circuit, there is not necessity to connect thesereinforcing electrode portions mutually with the second via hole VH2.Therefore, the first and second substrate reinforcing electrode portions30 b, 32 b are formed in a state that they are electrically insulatedmutually by the second interlayer insulating layer 22. In this case, thefirst substrate reinforcing electrode portion 30 b and the secondsubstrate reinforcing electrode portion 32 b may be connected via thesecond via hole VH2.

Then, as depicted in FIG. 7A, a solder resist 24 in which an openingportion 24 a is provided on the connection parts of the second wiringlayers 32 respectively is formed on both surface sides of the compositesubstrate 5. A film thickness of the solder resist 24 is about 20 μm.

Then, as depicted in FIG. 7B, a contact layer 34 is formed on theconnection parts of the second wiring layers 32 respectively on bothsurface sides of the composite substrate 5. As a preferred example ofthe contact layer 34, a nickel layer whose film thickness is set toabout 3 μm and a gold (Au) layer whose film thickness is set to about0.1 μm are formed in sequence from the bottom by the electrolessplating.

Then, bump electrodes 36 each connected to the contact layer 34 on thesecond wiring layer 32 and made of solder, or the like are formedrespectively on both surface sides of the composite substrate 5.

In this manner, a two-layered build-up wiring layer BW connected to theupper ends or the lower ends of the penetration conductors TC is formedrespectively on both surface sides of the composite substrate 5.

With the above, a wiring member 6 in which the build-up wiring layer BWis formed in a plurality of wiring substrate regions A (FIG. 4B) of thecomposite substrate 5 respectively is obtained. In the example in FIG.7B, the two-layered build-up wiring layer BW (the first and secondwiring layers 30, 32) is formed, but the build-up wiring layer can beformed in any n layers (n is an integer of 1 or more) (single layer orstacked layers).

Here, the build-up wiring layer BW may be formed only on one surfaceside of the composite substrate 5. In this case, the bump electrodesconnected to the penetration conductors TC are provided on the surfaceof the oxidized aluminum substrate portion 10 located on the oppositeside to the build-up wiring layer BW.

Then, as depicted in FIG. 8, the wiring member 6 in FIG. 7B is cut inthe part corresponding to the aluminum substrate portion 10 x (thecenter part (FIG. 4B) of the dicing region D) from the top surface tothe bottom surface. Thus, individual wiring substrates 1 are obtained.

As explained above, in the method of manufacturing the wiring substrateaccording to the first embodiment, first, the aluminum substrate 10 a inwhich a plurality of wiring substrate regions A are defined is prepared,and then the insulating resin layer 11 in which the opening portion 11 ais provided in the areas to be anodized respectively is formed.

Then, the aluminum substrate 10 a is anodized in the thickness directionthrough the opening portions 11 a in the insulating resin layer 11.Accordingly, the oxidized aluminum substrate portions 10 in which alarge number of fine holes H are provided respectively are formedpartially in the aluminum substrate 10 a.

Then, the aluminum portion 10 b left on the lower side is removed, andthus the through holes TH each of which penetrates the substrate in thethickness direction are provided in the oxidized aluminum substrateportions 10 respectively. Then, the penetration conductor TC is filledin a large number of through holes TH in the oxidized aluminum substrateportions 10 respectively.

By employing such manufacturing method, the oxidized aluminum substrateportion 10 whose substrate strength is weak is reinforced by thealuminum substrate portion 10 x whose substrate strength is strong.Therefore, the strength of the whole substrate can be improved ratherthan the case where the oxidized aluminum substrate is employed over thewhole area.

Accordingly, in various steps applied to form the build-up wiring layerBW that is connected to the penetration conductors TC provided in theoxidized aluminum substrate portions 10, such an event can be preventedthat the cracks are generated in the oxidized aluminum substrateportions 10. As a result, production yield of the wiring substrate canbe improved, and the wiring substrate whose reliability is high can beobtained.

As depicted in FIG. 8, in the wiring substrate 1 of the firstembodiment, the composite substrate 5 functioning as the core substrateis arranged in the center part in the thickness direction. The compositesubstrate 5 includes the oxidized aluminum substrate portions 10 thatare shaped squarely when viewed from the top, and the aluminum substrateportion 10 x having a frame shape, provided around the oxidized aluminumsubstrate portion 10.

The oxidized aluminum substrate portions 10 are obtained by anodizingthe aluminum substrate 10 a, and a large number of through holes TH eachof which penetrates the substrate in the thickness direction areprovided in the oxidized aluminum substrate portions 10. The penetrationconductor TC is filled in the through holes TH respectively, and thepenetration conductors TC function as the penetration vias that enablethe conduction between both surface sides of the oxidized aluminumsubstrate portion 10.

The first interlayer insulating layer 20 in which the first via holesVH1 are provided on the penetration conductors TC, which are caused tofunction as the penetration vias, out of a large number of penetrationconductors TC provided in the oxidized aluminum substrate portion 10, isformed on both surface sides of the composite substrate 5 respectively.The penetration conductors TC covered with the first interlayerinsulating layer 20 are electrically insulated mutually by the oxidizedaluminum substrate portion 10 (insulator), and have no concern in theconduction between the upper and lower sides.

Also, the first wiring layer 30 connected to the upper end or the lowerend of the penetration conductor TC via the first via hole VH1 is formedon the first interlayer insulating layer 20 on both surface sidesrespectively. The first wiring layer 30 is connected electrically to aplurality of penetration conductors TC in the connection parts betweenthe first wiring layer 30 and the penetration conductors TC.

Also, the first wiring layer 30 is formed to include the first wiringportions 30 a, and the first substrate reinforcing electrode portion 30b formed of the same layer as the first wiring portion 30 a.

The first wiring portions 30 a are arranged on both surface sidescorresponding to the oxidized aluminum substrate portion 10, and areconnected to the penetration conductors TC via the first via holes VH1.In contrast, the first substrate reinforcing electrode portion 30 b isarranged on both surface sides corresponding to the aluminum substrateportion 10 x, and is separated from the first wiring portions 30 a.

Further, the second interlayer insulating layer 22 in which the secondvia hole VH2 is provided on the connection parts of the first wiringlayer 30 respectively is formed on both surface sides of the compositesubstrate 5 respectively. The second wiring layer 32 connected to thefirst wiring layer 30 via the second via hole VH2 is formed on thesecond interlayer insulating layer 22 on both surface sidesrespectively.

Like the first wiring layer 30, the second wiring layer 32 is formed toinclude the second wiring portions 32 a, and the second substratereinforcing electrode portion 32 b formed of the same layer as thesecond wiring portions 32 a. Then, the second wiring portions 32 a arearranged on both surface sides corresponding to the oxidized aluminumsubstrate portion 10, and are connected to the first wiring portions 30a of the first wiring layer 30 via the second via holes VH2respectively. In contrast, the second substrate reinforcing electrodeportion 32 b is arranged on both surface sides corresponding to thealuminum substrate portion 10 x, and is separated from the second wiringportion 32 a.

The first and second substrate reinforcing electrode portions 30 b, 32 bare arranged with a ring-like connected pattern on the partscorresponding to the aluminum substrate portions 10 x.

Also, the solder resist 24 in which the opening portion 24 a is providedon the connection portions of the second wiring layer 32 respectively isformed on both surface sides of the composite substrate 5 respectively.The contact layer 34 formed of nickel/gold layers, or the like is formedon the connection parts of the second wiring layer 32 on both surfacesides respectively.

Also, the bump electrodes 36 each connected to the contact layer 34 onthe second wiring layer 32 are formed on both surface sides of thecomposite substrate 5 respectively.

In the wiring substrate 1 of the first embodiment, the first via holesVH1 in the first interlayer insulating layer 20 are arranged in anypositions of the oxidized aluminum substrate portion 10 in which a largenumber of penetration conductors TC are provided in advance. Therefore,the penetration via structure that enable the conduction between bothsurface sides of the substrate can be easily constructed.

Also, the aluminum substrate portion 10 x whose substrate strength isstrong and which is shaped like a frame is provided and coupled aroundthe oxidized aluminum substrate portions 10 in which a large number ofpenetration conductors TC are provided and whose substrate strength isweak. That is, in the wiring substrate 1 of the first embodiment, thestiffener (reinforcing plate) formed of the aluminum substrate portion10 x is coupled to the outer edge side of the wiring substrate, andstrength of the substrate is reinforced.

As a result, strength of the substrate can be improved rather than thecase where the oxidized aluminum substrate portion 10 is employed overthe whole area (the related art).

Also, strength of the substrate can be improved from such a viewpointthat the first and second substrate reinforcing electrode portions 30 b,32 b of the first and second wiring layer 30, 32 are arranged on bothsurface sides of the aluminum substrate portion 10 x as the reinforcingmember. Further, the wiring substrate 1 has a symmetric structure withrespect to the composite substrate 5, and thus an occurrence of a warpcan be prevented.

Also, the outer edge part of the oxidized aluminum substrate portion 10in which a large number of penetration conductors TC are provided isprotected by the aluminum substrate portion 10 x, and is not exposed tothe outside. As a result, even though a mechanical impact is applied tothe end part of the wiring substrate 1, it is not feared that thedefects are caused such that the penetration conductors TC fall to peeloff, and the like, and also the wiring substrate with high reliabilitycan be constructed.

In the wiring substrate 1 in FIG. 8, the bump electrodes 36 formed onthe upper surface side serve as the chip connection parts connected tothe semiconductor chip, and the bump electrodes 36 formed on the lowersurface side serve as the external connection parts connected to themounting substrate (the mother board, or the like).

Then, as depicted in FIG. 9, the connection parts of a semiconductorchip 40 (LSI chip) are flip-chip connected to the bump electrodes 36formed on the upper surface side of the wiring substrate 1 in FIG. 8 bythe reflow soldering. Also, an underfill resin may be filled in aclearance between the semiconductor chip 40 and the wiring substrate 1.

Accordingly, a semiconductor package (semiconductor device) 2 of thefirst embodiment is obtained. In the semiconductor package 2, for thesimilar reason, strength of the substrate can be improved and also highreliability can be obtained.

Second Embodiment

FIGS. 10A to 10C are sectional views depicting a method of manufacturinga wiring substrate and a semiconductor package according to a secondembodiment.

A feature of the second embodiment resides in that the insulating resinlayer 11 used as the above mask for the anodic oxidization in the firstembodiment (FIG. 4B to FIG. 5A) is not removed and is still left.

Therefore, in the second embodiment, a wiring member 6 a depicted inFIG. 10A is obtained. That is, the insulating resin layer 11 (the dotshaded portion) is left on the upper surface of the aluminum substrateportion 10 x of the composite substrate 5, and then the first interlayerinsulating layer 20 is formed on the insulating resin layer 11.

In the case that the insulating resin layer 11 is left as in the secondembodiment, preferably a permanent resist that can be used as theinterlayer insulating layer, as it is, is employed.

Then, as depicted in FIG. 10B, like the first embodiment, the wiringmember 6 a in FIG. 10A is cut in the dicing region D (FIG. 4B), and thusindividual wiring substrates 1 a are obtained.

The second embodiment is similar to the first embodiment except that theinsulating resin layer 11 is left.

In the second embodiment, the step of removing the insulating resinlayer 11 can be omitted. Therefore, a lower cost can be achieved ratherthan the first embodiment.

Then, as depicted in FIG. 10C, like the first embodiment, the connectionparts of the semiconductor chip 40 are flip-chip connected to the bumpelectrodes 36 formed on the upper side of the wiring substrate 1 a inFIG. 10B, and thus a semiconductor package (semiconductor device) 2 a isconstructed.

Third Embodiment

FIGS. 11A to 11C are sectional views depicting a method of manufacturinga wiring substrate and a semiconductor package according to a thirdembodiment.

As depicted in FIG. 11A, a feature of the third embodiment is that thefirst interlayer insulating layer 20 formed at first in the method offorming the build-up wiring layer BW in the above first embodiment(FIGS. 5C and 5D) is omitted.

Therefore, as depicted in FIG. 11A, in a wiring member 6 b obtained inthe third embodiment, the first wiring portions 30 a of the first wiringlayer 30 are formed directly on both surfaces of the oxidized aluminumsubstrate portion 10 without intervention of the first interlayerinsulating layer 20, and also the first substrate reinforcing electrodeportion 30 b of the first wiring layer 30 is formed directly on bothsurfaces of the aluminum substrate portion 10 x.

Then, as depicted in FIG. 11B, like the first embodiment, the wiringmember 6 b in FIG. 10A is cut in the dicing region D (FIG. 4B), and thusindividual wiring substrates 1 b are obtained.

In the third embodiment, the first substrate reinforcing electrodeportion 30 b of the first wiring layer 30 is formed to contact thealuminum substrate portion 10 x. In this case, the first substratereinforcing electrode portion 30 b and the aluminum substrate portion 10x are not connected to the electric circuit, and therefore no troublearises.

The third embodiment is similar to the first embodiment except the firstinterlayer insulating layer 20 is omitted.

In the third embodiment, the first substrate reinforcing electrodeportion 30 b is formed directly on both surfaces of the aluminumsubstrate portion 10 x. Therefore, a thickness of the aluminum substrateportion 10 x as reinforcement is substantially increased. As a result,strength of the substrate can be improved in contrast to the first andsecond embodiments.

Also, the steps of forming the first interlayer insulating layer 20 andthe first via holes VH1 can be omitted. Therefore, a lower cost can beachieved rather than the first embodiment.

Then, as depicted in FIG. 11C, like the first embodiment, the connectionparts of the semiconductor chip 40 are flip-chip connected to the bumpelectrodes 36 formed on the upper side of the wiring substrate 1 b inFIG. 11B, and thus a semiconductor package (semiconductor device) 2 b isconstructed.

Fourth Embodiment

FIGS. 12A to 12C are sectional views depicting a method of manufacturinga wiring substrate and a semiconductor package according to a fourthembodiment.

A feature of the fourth embodiment resides in that, like the secondembodiment, the insulating resin layer 11 (FIG. 4B to FIG. 5A) used asthe mask for the anodic oxidization is still left and, like the thirdembodiment, the first interlayer insulating layer 20 of the build-upwiring layer BW (FIGS. 5C and 5D) is omitted.

Therefore, as depicted in FIG. 12A, in a wiring member 6 c obtained inthe fourth embodiment, the first wiring portions 30 a of the firstwiring layer 30 are formed directly on both surfaces of the oxidizedaluminum substrate portion 10 without intervention of the firstinterlayer insulating layer 20. Also, in the upper surface side of thealuminum substrate portion 10 x, the first substrate reinforcingelectrode portion 30 b of the first wiring layer 30 is formed via theinsulating resin layer 11 (the dot shaded portion), but in the lowersurface side of the aluminum substrate portion 10 x, the first substratereinforcing electrode portion 30 b is formed directly withoutintervention of the insulating layer.

Then, as depicted in FIG. 12B, like the first embodiment, the wiringmember 6 c in FIG. 12A is cut in the dicing region D (FIG. 4B), and thusindividual wiring substrates 1 c are obtained.

The fourth embodiment is similar to the first embodiment except theinsulating resin layer 11 is left and the first interlayer insulatinglayer 20 is omitted.

In the fourth embodiment, the step of removing the insulating resinlayer 11, the step of forming the first interlayer insulating layer 20,and the step of forming the first via holes VH1 can be omitted.Therefore, a lower cost can be achieved rather than the first to thirdembodiments.

Then, as depicted in FIG. 12C, like the first embodiment, the connectionparts of the semiconductor chip 40 are flip-chip connected to the bumpelectrodes 36 formed on the upper side of the wiring substrate 1 c inFIG. 12B, and thus a semiconductor package (semiconductor device) 2 c isformed.

Other Embodiment

In the above-mentioned first to fourth embodiments, the wiring substrateis manufactured by building the build-up wiring layer BW onto thecomposite substrate 5. As other mode, the wiring member (the wiringsubstrate) may be manufactured based on preparing in advance the wiringmember having the connection part apart from the composite substrate 5,and then bonding the connection parts of the wiring member onto thepenetration conductor TC of the composite substrate 5 by usingconductive material such as solder, or the like.

All examples and conditional language recited herein are intended forpedagogical purpose to aid the reader in understanding the invention andthe concepts contributed by the inventor to furthering the art, and areto be construed as being without limitation to such specifically recitedexamples and conditions, nor does the organization of such examples inthe specification relates to a showing of the superiority andinteriority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

1. A wiring substrate, comprising: a composite substrate including anoxidized aluminum substrate portion in which a large number ofpenetration conductors penetrating in a thickness direction areprovided, and a frame-like aluminum substrate portion provided aroundthe oxidized aluminum substrate portion; and a wiring layer of n layers(n is an integer of 1 or more) connected to the penetration conductors.2. A wiring substrate according to claim 1, wherein the wiring layer isconnected electrically to a plurality of said penetration conductors ina connection part between the wiring layer and the penetrationconductors.
 3. A wiring substrate according to claim 1, wherein thewiring layer includes a wiring portion which is arranged in a partcorresponding to the oxidized aluminum substrate portion and isconnected to the penetration conductors, and a substrate reinforcingelectrode portion which is arranged in a part corresponding to thealuminum substrate portion and is separated from the wiring portion. 4.A wiring substrate according to claim 3, wherein the substratereinforcing electrode portion is arranged with a ring-like connectedpattern.
 5. A method of manufacturing a wiring substrate, comprising:preparing a composite substrate, which includes a plurality of oxidizedaluminum substrate portions in each of which a large number ofpenetration conductors which penetrate in a thickness direction areprovided, and an aluminum substrate portion which couples the pluralityof oxidized aluminum substrate portions; and forming a wiring layer of nlayers (n is an integer of 1 or more) connected to the penetrationconductors.
 6. A method of manufacturing a wiring substrate, accordingto claim 5, wherein the wiring layer is connected electrically to aplurality of said penetration conductors in a connection part betweenthe wiring layer and the penetration conductors.
 7. A method ofmanufacturing a wiring substrate, according to claim 5, wherein thepreparing of the composite substrate includes forming an insulatingresin layer, in which opening portions are provided in areas where theoxidized aluminum substrate portions are obtained, on an aluminumsubstrate, obtaining the oxidized aluminum substrate portions in which alarge number of holes are provided, by anodizing the aluminum substratein a thickness direction through the opening portions of the insulatingresin layer, obtaining the oxidized aluminum substrate portions in whicha large number of through holes penetrating in a thickness direction areprovided, and the aluminum substrate portion coupled to the oxidizedaluminum substrate portions, by removing an aluminum portion on a lowerside of the oxidized aluminum substrate portions until the holes areexposed, and filling the penetration conductors in the through holes. 8.A method of manufacturing a wiring substrate, according to claim 5,wherein, in forming the wiring layer, the wiring layer is formed toinclude a wiring portion which is arranged in a part corresponding tothe oxidized aluminum substrate portion and is connected to thepenetration conductors, and a substrate reinforcing electrode portionwhich is arranged in a part corresponding to the aluminum substrateportion and is separated from the wiring portion.
 9. A method ofmanufacturing a wiring substrate, according to claim 8, wherein, informing the wiring layer, the substrate reinforcing electrode portion isarranged with a connected pattern to surround the oxidized aluminumsubstrate portion.
 10. A method of manufacturing a wiring substrate,according to claim 5, after forming the wiring layer, furthercomprising: obtaining an individual wiring substrate including aframe-like aluminum substrate portion on an outer edge side, by cuttinga part corresponding to the aluminum substrate portion.